The present invention generally relates to a fast tool change holder for holding a tool adapter onto a drive spindle and, more particularly, to a fast tool change holder for holding a tool adapter onto a high speed drive spindle by utilizing the pressure of the coolant fluid supplied from the drive spindle to a tool on the tool adapter.
Various types of arrangements are known to clamp a tool adapter onto a tool holder, and hence a drive spindle. One such arrangement comprises using a mechanical fastening means, such as a bolt, which extends from an outer end of the tool adapter, through a central opening in the tool adapter and into the tool change holder. The bolt threadedly engages within an opening in the tool change holder in order to clamp the tool adapter onto the tool change holder, and hence to the spindle. This clamping arrangement is inefficient and tedious since, in order to change tool adapters on the drive spindle, an operator must manually remove the bolt from the tool change holder, change the tool adapters and reinsert the bolt into the tool change holder.
A further known arrangement for clamping a tool onto a drive spindle comprises a tool adapter having a conical end portion which is capable of being received within a conical recess of a tool change holder. The tool change holder further includes a central opening connected with the recess for housing a piston therein. The piston has grippers at one end thereof for engaging a pin extending out from the conical end portion of the tool adapter. The piston is spring biased in a direction away from the tool adapter in order to exert a substantially constant inwardly directed pulling force upon the tool adapter.
As the piston is biased away from the tool adapter, the grippers are pulled within the recess of the tool change holder and contract towards one another as they move along a camming surface located within the recess. As a result, the gripPers are able to grasp the pin on the tool adapter and pull it inwardly into the recess. After pulling the tool adapter into the recess, the grippers further act to lock the adapter within the tool holder.
The tool adapter may be released from the tool change holder by means, such as a hydraulic ejector, which exerts a force upon the piston in a direction toward the tool adapter. This force acting upon the piston serves to overcome the spring force exerted upon the piston so that the grippers can open and release the tool adapter from the recess of the tool holder.
This clamping arrangement is also inefficient and tedious since, in order to change tool adapters on the spindle, an operator must first actuate the hydraulic ejector to release the grippers from the first tool adapter, change the tool adapters and subsequently engage the grippers with the second tool adapter. Further, this clamping system is disadvantageous because it requires a plurality of mechanical and hydraulic parts located within the tool holder for clamping the tool adapter therein. Such parts create added expense to the price of the tool holder and are problematic to maintain.
U.S. Pat. No. 4,677,792 discloses an arrangement for holding a bushing having a grinding wheel connected thereto onto a coupling element connected to a drive spindle. The coupling element is formed as a hydraulic expansion element which includes a thin-walled cylindrical expansion sleeve on an outer portion thereof and a bore centrally located therein. Oil is filled within the bore and the expansion sleeve. The oil within the expansion sleeve and the bore is capable of being compressed by a piston which slides within the bore. A bolt, which is screwed into a threaded extension of the bore, engages with the piston to move the same within the bore in order to compress the oil in the bore and the expansion sleeve. By compressing the oil within the bore and the expansion sleeve, the latter will expand radially outwardly and clamp the bushing onto the coupling element.
This system is also inefficient and tedious because an operator must manually perform numerous steps in order to change bushings on the coupling element. First, an operator must release the frictional grip between the expansion sleeve and the first bushing. This is done by engaging the bolt within the bore with a tool to decompress the oil within the expansion sleeve. The operator must then change the bushings on the coupling element and subsequently reinsert the tool to re-engage the bolt in order to compress the oil within the expansion sleeve to secure the second bushing onto the coupling element. Accordingly, there is a need for an improved fast tool change holder whereby an operator may quickly and efficiently change tool adapters on a drive spindle.